The invention relates in the first instance to a method for the carrying out of a microbiological or enzymatic process in which reaction components are fed into a reactor constructed as an endless circulation tube and a circulation current is brought about inside the said tube.
A method of this type is known from the published French Patent Application 2,209,837.
It is usual to carry out microbiological or enzymatic processes in a vessel provided with one or more stirring elements (see for example the published European Patent Application 0,111,253). It has become evident that when a reactor of this type is used, a considerable spread occurs in the reaction time, i.e the time that a small element of liquid requires in order to be conveyed around through the vessel starting from the stirrer and to be conveyed back to the stirrer. This spread has an unfavourable influence on the yield of the process since the liquid particles with a relatively rapid circulation time will be subjected too briefly to the treatment (inadequate conversion), whereas liquid particles with a slow circulation time will be exposed too long to the treatment. In certain processes the viscosity increases during the fermentation process and from a certain viscosity value upwards the stirrer generates a revolving cylinder while the remainder remains essentially stationary. In the case of aerobic fermentation processes, to promote the multiplication of aerobic bacteria and their product formation, air is supplied to the reaction mixture. If a stirred container is used, a relatively high oxygen concentration may occur at the stirrer and a relatively low oxygen concentration at the vessel wall. These disadvantageous phenomena are intensified as the rheological properties of the mixture change. In order, nevertheless, to achieve as complete a reaction as possible, high energy costs are often necessary, the energy being primarily used for the stirring. Another problem of carrying out a process in a stirred container is that enlargement (scaling up) of the equipment from the laboratory scale to the industrial scale is accompanied by a considerable change in the conditions under which the process proceeds.
These drawbacks are not removed by the method according to the said French Patent Application 2,209,837 since there are located inside the tube driven propellers which provide both for the circulation and for the mixing by means of stirring. To this known method there also pertain the disadvantages of high energy costs, relatively low yield and uncontrollable differences in oxygen concentration.